Nonpickable keyhole lock



J une IG, 1931. I HUGHES 1,810,400

NONPICKABLE KEYHOLE LOCK Filed April 4, 1927 FrederickT Hqghes Patented. June 16,; 1931 UNITED" STATES PATENT ()FlFICE- FREDERICK r. Ensues, or

NonrIc ABLn Application filed April 4,

This inventionrelates to a lock attachment of the type which has come into use and which is inserted in an ordinary key hole in I a door. These look attachments are miniature pin tumbler or cylinder locks. They are thrust into the key hole from one side of the door and are usually provided with a springpressed dog which becomes extended or projeoted from thestem of the device after it is placed in the keyhole, and this dogoperates to prevent the withdrawal, of the miniature.

lock. In this way, an ordinary lockwhich,

mit the inserted lock to pass into the key hole; this dog is spring-pressed, and as the inserted lock is shoved home hole, the dog springs up behind a part of the regular lock of the door'and prevents the inserted look from being removed except by the useof the pin tumbler type'key inserted in, the miniaturelock. When this ,pin tumbler type key is inserted, the stem of the inserted lock can be rotated so as to swing the dog down into a position which will enable I the dog to permit the withdrawal of the inserted lock. The presence of this inclined edge 011 the'log, however, renders it possible to pick such a lock, and this is accomplished by inserting an instrument from-the sideof the door opposite to that at which the miniature'lock is inserted. The instrument can be moved along until its'ends strike the in-.

clined" edge of the-dog and in this way the dog can be moved down into its folded or retracted position, after whichthe inserted lock can be shoved outof the keyhole. The general object of this invention is to overcome this difiiculty and to produce a key hole lock of this type which can not be picked in the manner'suggested. More-specifically stated,

- F urtherobjeots of the A preferred embodiment trating a key hole lock of the type referred in the key LosANeELEs, CALIFORNIA KEYHOLE LOCK 1 9 27. Serial No. 180,789.

the principal object of the inventionis to provlde such a key hole lock with a detent dog forholding tin the door, constructed in such a way that 1t .can not be manipulated-by any instrument inserted from the outside of the door 111 such a way as to retract the dog or fold it 1nto its retracted position.

invention will appear hereinafter.

he invention consists of the novel parts and oomblnationof parts to be described herelnaftenall of which contribute to roduce an efficient non-pickable key hole ock.

of the invention isdescrlbed .111 the following specification,v While the broadscope of the invention is pointed out intheappended claims.

Thedrawlngiis a vertical section through ZLPOIUOD of a door at the key hole and illusto inserted in the key hole. This view shows v a portion of the tubular stem of the key hole lock broken away so as to ferred'construction of the detent or dog.

eferrlng more particularly to the parts, 1; representsone of the plates of a regular: door lock which is used inconnection'with a regularward-typekey. This regularlock'is mounted 1n the middleplane of the door 2, the outer faces of the door being provided 8 W13? escutcheons 3.. g I

g'he key holee is formed through the door through-these escutcheonsin the usual illustrate the preand way. a The keyhole. lock embodying my inventlon is constructed "so as to enable it to be slipped into the key hole inthe usual manner from one side of the door; and it is provided with a retractable detent to engage-a part wlthin'the door to prevent withdrawal of a the lock: 7 According to myinvention I give H this detent a contour which will operateto prevent it from being retracted to disengage it from the doorbyran instrument inserted from theother side of thedoor. The detent ls preferably constructed so that, when the lock is inserted in; the key hole, it moves laterally outwardly from the axis of the key hole, so as to engage a part of the door, for example, the plate 1.2. The key hole lock is v in which it is illustrated.

cam edge inserting to prevent the key-hole lock provided with key controlled means for effecting the rotation of the detent on the axis of the key hole into a position which will permit the withdrawal of the ke -hole lock.

In the present embodiment of the invention, the key hole lock comprises a casing 5 which has the general contour in cross section of the key hole, that is to say, its upper end is formed into a barrel 6 and its lower portion is formed into a block 7 which carries the sliding pins 8 of the key hole lock. Vithin the barrel 6 the inner portion 9 of a stem 10 is rotatably 11, the wavy edge of the key will hold the pins 8 in the proper position to enable the stem 9 to be rotated.

The stem 10 of the lock is provided I a retractable detent or dog 12 which is preferably mounted to move laterally in a. transverse slot 13in the'stem. The stem 10 is preferably tubular and the detent or dog 12 is spring-pressed toward its extended position complished by means of a coil spring 14 mounted in the end of the stem 10 beyond the dog 12. The dog is mounted to rotate on a pivot pin 15 and its end is provided with a 16. In the end of the stem 10 beyond the dog, a ball 18 is provided which is held against the cam edge 16 by the spring 14. This holds the detent 12 normally extended but permits it to be forced inwardly.

The inner end of the block 7 of the keyhole lock casing is formed into a guide shoe or spur 19 which projects forwardly and guides the lower end of the key-hole lock as it is thrust into position. The dog 12 projects upwardly from the stem 10 as indicated and is provided with an inclined face or edge 20. When the key-hole lock is being inserted in the key hole, this edge 20 strikes the upper edge 21 of the key hole in one of the escutcheons 3 and this swings the dog down into its retracted position. When the movement is completed, the spring 14 swings the dog 12 up so that it projects above the edge .22 of the opening in the plate 1. \Vhen this occurs, a shoulder 23 on the casing 7 Y of the key-hole lock will have engaged the outer face of the plate 1. In this way the dog and the shoulder 23, cooperate from being removed. V i

In orderto remove the key-hole lock to perinit the regular key to be inserted, it is simply necessary to insert the key 11 and rotate it.-

Thiswill rotate the stem 10 so as to bring the dog 12, down into a lower position in line with the lower portion ofthe key hole. After this has been done, the key-hole lock can be readily withdrawn and will pull out of the key hole with the key 11.

According to my invention, I give the detent a contour such that an instrument inserted in the key hole cannot retract the de-- mounted. By inserting a key with This may be ac-- tent, that is, from the outer end 25 of the key hole. In other words, I make the inclined face inaccessible by constructing the detent so that such an instrument can not be brought into contact with the inclined edge. In the present embodiment, this inclined edge 20 does not extend from the outer portion of the dog inwardly until it reaches the side of the stem, but the inner portion 24 of this inclined edge or face is cut away so as to produce a recess in the form of an undercut notch 26 at this point. \Vith a dog embodying my invention, if an instrument is inserted at the point 25 and above the stem 10, its end can not come into contact with the inclined edge 20 and the undercut notch 26whcn engaged by such an instrument is incapable of swinging the dog sufiiciently to extract it. Hence, the insertion of such an instrument can not move the dog down so as to clear the edge 22 and permit the key-hole lock to be forced out of the key hole.

It is understood that the embodiment of the invention described herein is only one of the many embodiments this invention may take, and I do not wish to be limited in the practice of the invention, nor in the claims to the particular embodiment set forth.

\Vhat I claim is:

1'. A non-pickable structed to be slipped into the key hole from one side of the door and having a detent to engage apart within the door to prevent withdrawal of the lock, said detent having a contour operating to prevent the same from being disengaged by an instrument inserted from the other side of the door.

2. A non-pickable key hole lock constructed to be slipped into the key-hole from one side of the door and having a movable de-- tent to engage a part within the door to prevent withdrawal of the key-hole lock, and key controlled means for moving the detent into a position to permit the withdrawal of the lock, said detent having a contour at its inner end incapable of moving the detent and operating to prevent the same from being disengaged from the door byan instrument inserted in the key of the door.

3. A non-pickable key hole lock constructed to he slipped into the key hole from one side of the door and having a detent mounted for rotation on the axis of the key holev and movable laterally with respect to the axis of the key hole to engage a portion of the door when the key hole lock is inserted, and therebyprevent withdrawal of the lock, said detent having a contour adjacent its in ner-end operating to render it incapable 0 being moved'radially inwardly toward the axis of the key-hole by an instrument inserted from the other'side of the door.

4. A non-pickable key-hole lock having key-hole lock conhole from the other side engaging its inner end adjacent the stem, thereby preventing, the same from being moved inwardly toward the axis of the stem by an instrument inserted from the other side of the door.

5. In an non-pickable key-hole lock, the

combination of a lock casing constructed to be slipped into the key hole from one side of the door, a retractable detent having a face operating to engage a portion of the key hole to retract the detent when the lock casing is being slipped into the key hole, said detent operating to engage a part within the door to preventwithdrawal of the casing, said face being located to one side of the key-hole,

and in a position to be inaccessible to an instrument inserted through the keyhole from the outer side of the door.

6. In a non-pickable key-hole lock for a door, the combination of a lock casing constructed to be slipped into the key hole of adoor lock from one side of the door and having a stem projecting at one end of the casing toward the other side of the door, a spring-pressed dog carried by'the stem for engaging a part within the door to prevent, withdrawal of the lock casing from the key I hole, said dog having an inclined face operating to engage a portion of the key hole and retract the dog when the lock casing is being slipped into the key hole, said dog having a recess in a position to be engaged by an instrument thrust into the key hole from the opposite side and operating to prevent said instrument from engaging the inclined face to retract the dog.

7. In a non-pickable key-hole lock for a key hole in a door, the combinationof a lock casingconstructed to be slipped into the key 7 hole of the door look from one side of the door and having a stem projecting at one end of the casing toward the other side of the door, said stem having a transverse slot therein, a spring-presseddog carried by the stem in the slot and operating to engage a.

portion of the door lock to prevent withdrawal of the lock casing fromthe key hole,

I cannot be engaged by an instrument thrust into the key hole from the opposite side, said dog having a form at its inner end rendering the dog incapable of retracting rotation.

8. A non-pickable keyhole lock constructed to be slipped into the key hole from one side of the door and having a detent to engage a part within the door to prevent withdrawal of the lock, said detent having a contour adj acent its inner end operatingflto prevent the detent from being disengaged by an instrument inserted from the other side of the door.

- 9. A non-pickable keyhole lock constructed to he slipped into the keyhole from one side of the door and having a detent to engage a part within the door to prevent withdrawal of the lock, the key control means for rotating the detent into a position to permit the with-.

drawal of the look, said detent havingan inclined edge facilitating its passage, into the keyhole, said inclined-edge having a contour adjacent its inner end operating to prevent the inclined edge from beingengaged by an instrument inserted in the keyhole from the other side of the door.

Signed at-Los Angeles, Calif., this 18th day of Maroh,.l927.

FREDERICK T. HUGHES. v

said clog having ,aninolined face operating to engagea portion of the key hole. and retract the dog when the casing is being slipped into the key hole, said inclined face being located at a point removed from the adjacent side of the stem and ina position in which it 

